The coccidia (Apicomplexa: Eimeriidae) of Caudata (Amphibia), with descriptions of two new species from North America

Abstract

Over 300 caudate Amphibia were surveyed for coccidia in North America. Two new species of coccidia (Apicomplexa: Eimeriidae) are described. Oocysts of Eimeria opacum sp.nov. from Ambystoma opacum are spherical to subspherical, rarely ellipsoidal, 29.5 × 28.1 (27–32 × 22–31) μm, and have a shape index (length/width) of 1.05 (1.0–1.4). A micropyle, oocyst residuum, and polar granule are absent. Sporocysts are ellipsoidal to kidney-bean shaped, 17.4 × 9.1 (16–21 × 8–11) μm, with a shape index of 1.92 (1.6–2.3). Sporocysts are unusual in that they are encased in a second, more fragile wall that thins to form membranes at the poles; Stieda and substieda bodies are absent. Oocysts of Isospora hightoni sp.nov. from Plethodon albagula are spherical, rarely subspherical, 22.9 × 22.8 (21–24 × 21–24) μm, with a shape index of 1.0 (1.0–1.04). A micropyle and polar granule are absent, but a delicate oocyst residuum was noted in 13/40 (33%) of the oocysts. Sporocysts are ellipsoidal, 16.6 × 11.1 (14.5–17.5 × 10.5–12) μm, with a shape index of 1.5 (1.4–1.6); Stieda and substieda bodies are present. In addition to the species described herein, a taxonomic summary is provided of the known coccidia from Caudata, with the species E. nipponensis sp.nov., E. pyrrhogaster sp.nov., and E. saitamaensis sp.nov. assigned to previously reported coccidia erroneously assigned to named species.